Enable optimization of top-level code.

src/hydrogen-instructions.h

Index: src/hydrogen-instructions.h
===================================================================
--- src/hydrogen-instructions.h	(revision 10686)
+++ src/hydrogen-instructions.h	(working copy)
@@ -97,6 +97,7 @@
   V(CompareConstantEqAndBranch)                \
   V(Constant)                                  \
   V(Context)                                   \
+  V(DeclareGlobals)                            \
   V(DeleteProperty)                            \
   V(Deoptimize)                                \
   V(Div)                                       \
@@ -1486,6 +1487,33 @@
 };
 
 
+class HDeclareGlobals: public HUnaryOperation {
+ public:
+  HDeclareGlobals(HValue* context,
+                  Handle<FixedArray> pairs,
+                  int flags)
+      : HUnaryOperation(context),
+        pairs_(pairs),
+        flags_(flags) {
+    set_representation(Representation::Tagged());
+    SetAllSideEffects();
+  }
+
+  HValue* context() { return OperandAt(0); }
+  Handle<FixedArray> pairs() const { return pairs_; }
+  int flags() const { return flags_; }
+
+  DECLARE_CONCRETE_INSTRUCTION(DeclareGlobals)
+
+  virtual Representation RequiredInputRepresentation(int index) {
+    return Representation::Tagged();
+  }
+ private:
+  Handle<FixedArray> pairs_;
+  int flags_;
+};
+
+
 class HGlobalObject: public HUnaryOperation {
  public:
   explicit HGlobalObject(HValue* context) : HUnaryOperation(context) {